Ion producing mechanism



April 14, 1959 I F. F. CPPENHEIMER ,4

ION PRODUCING MECHANISM Filed June 28, 1946 2 Sheets-Sheet 1 ATTORNEYApril .1959 F. Fl OPPENHEIMER 2,882,411

ION PRODUCING MECHANISM Filed June 28, 1946 2 Sheets-Sheet 2 i. 1 a 48 fINVENTOR. fkAA/K OPPf/W/f/Mfk A YTOHNEY United States Patent IONPRODUCING MECHANISM Application June 28, 1946, Serial No. 679,883 6Claims. (Cl. 250-419) This invention relates to calutrons and moreparticularly to means for introducing gas at selected points in the arcchamber of a calutron ion source.

Calutrons are described in general in Atomic Energy for MilitaryPurposes by H. D. Smyth and in greater detail in US. Patent No.2,709,222, to Ernest 0. Lawrence, which issued on May 24, 1955.Calutrons have in separating the isotopes of uranium for military energypurposes. In general, ions of a polyisotopic mixture of a desiredelement are formed and projected into a magnetic field. Thereafter, theions travel in curved paths, the ions of greater mass describing flattercurves than the ions of lesser mass. Suitable collectors are placedalong each path, preferably at the 180 point in each curve. The ions arethere neutralized and collected substantially separated from ions ofdifferent mass.

The ions are formed in an arc discharge that takes place in a vaporcontaining the desired element, for example, uranium tetrachloride hasbeen used for producing uranium ions. This are discharge takes place ina confined region designated as an arc chamber. time to time it has beenfound that the arc is unsteady, particularly in the anode region of thearc discharge. I have discovered that this unsteadiness in the arc may'be remedied to a certain extent by introducing all of or part of thecharge gas at the region of the anode. The resulting arc is muchsteadier, resulting in an ion beam of increased current.

It is therefore an object of the present invention to provide a calutronare that is fairly reliable and steady.

Another object of the invention is to provide means for directing all ofor part of a charge vapor toward the anode of a calutron arc discharge.

Othere objects and advantages of-the invention will be apparent in thefollowing description and claims considered together with theaccompanying drawings, in which: I

looking along the magnetic tank and ion source secured Figure l isa planview field of 'a'calutron vacuum to the vacuum tank;

Fig. 2 is an enlarged sectional view of the arc block portion of Fig. 1,taken along the line 2-2 of Fig. 1;

Fig. 3 is an isometric view of the anode region of the arc block of Fig.2; and

Fig. 4 is a modified form of the invention wherein the entire charge gasis introduced at the anode.

Fig. 5 is a partial cross sectional view of a modified form of theinvention wherein the charge gas is introduced at the base of the arcchamber.

Referring to Fig. 1, a generally tubular vacuum tank has a branchconnection 11 leading to suitable vacuum pumps for reducing the pressurewithin the tank to a desired level, such as 10" or 1O mm. Hg. Secured toan outer face plate 12 of the vacuum tank 10 is a metal tube 13supporting adjusting mechanism 14 for a stem assembly 15 projectingtherefrom and back through the tube 13 and having an arc block assembly16 supported From on its inner end. A liner 17 is mounted within thevacuum tank 10 on insulators 18 and a suitable negative electricpotential is maintained thereon to attract positive ions from the arcblock 16. A magnetic field 19 (Fig. 2) permeates the entire structure.Two plates 21 are attached to the liner 17 opposite the arc block 16 anddefine an elongated slit 22.

In the general operation of the calutron, positive ions are generated inthe are block 16 and because of the negative potential on the liner 17are attracted thereto and pass through the slit 22, thereafterdescribing gen? erally circular paths through the magnetic field.Suitable collectors (not shown) are utilized, as previously mentioned.

Referring to Figs. 1 and 2, the arc block 16 is sup portedon the end ofa tubular stem 23 of the stem assembly 15 by means of a spider-likebracket 24 designed 29 is an arc housing 31 to reduce the conduction ofheat to a minimum from the arc block 16 to the stern assembly 15.Secured to the spider 24 is a reservoir housing 25 having a reservoirchamber 26 formed therein and heated by two e1ec been principallyemployed and very successfully employed tric resistance heaters 27. Anipple 28 secured to the left side (Fig. 2) of the reservoir housing 25communicates the chamber 26 with a distributing chamber 29. Secured onthe outer end of the distributing chamber communicating with thedistributing chamber 29 by an upper aperture 32 and a lower aperture 33.The are housing 31 defines an arc chamber 34 having a restricted outletformed by two arc slit plates 36.

Electrons are obtained for the arc discharge from a filament 37 heatedto emissivity by a conductive curhundred volts negative 'with rentsupplied by two water-cooled leads 38. The filament 37 is insulated fromthe reservoir, distributing chamber, and are housing 31 and maintainedat several respect thereto. The collimating effect of the magnetic fieldcauses the electrons emitted from the filament 37 to describe a narrowribbon of emission down along the length of the arc chamber 34. An anode39 is provided for intercepting these electrons and although the anode39 may be maintained at any desired potential, I prefer to maintain itat the same potential as the arc housing 31.

The detailed structure of the vapor flow in accordance with theinvention is shown in Figs. 2 and 3. An L-shaped baflie 41 is securedadjacent to the lower vapor aperture 33 to direct the flow of vapor atthe anode 39.

In operation, a charge bottle of any desired type is inserted in thereservoir chamber 26 and contains a material that may "be vaporized bythe application of heat. Heat is supplied by the heaters 27 generatingvapor which fills the reservior chamber 26 and flows through the nipple28 into the distributing chamber 29. The vapor then flows out throughthe upper aperture 32 and the lower baffied aperture 33 into the arcchamber 34. The vapor is here bombarded by electrons from the filament37 that travel along the magnetic field until they strike the anode 39.Positive ions are formed in this are discharge and are withdrawn forutilization, as previously mentioned. The presence of the bafiie 41directing a substantial part of the flow at the anode 39 greatlyincreases the stability of the arc, resulting in a more prodigious andsteady formation of ions.

Referring to Fig. 4, there is shown a modification of my inventionwherein the entire gas fiow is directed at the anode. An arc block 45 isformed of a single piece of metal, such as copper, and is maintained ata potential positive with respect to an emissive filament 46. The block45 contains two interconnected reservoir bores 47 and an, arc chamberbore 48. The output vapor from the bores '47 is directed into a bore. 49to which is con.- necteda tubular member 51 directing the vapor flow tothe bottom of the arc chamber bore 48. The tube 51 .has an outletaperture 52 that directs the gas flowupwardly towardthe filament 46.Further, the filament 46 is so positioned with respect to the magneticfield and the outlet 52 that the electrons emittedtherefrom actuallyenter the outlet 52 of the tube 51.

inseam In operation of the modification of Fig. 4, an appropnate chargematerial is placed in the reservoir bores 47 and heated by heaters (notshown) causing vapor to be formed that travels through the tube 51 andthence upwardly through the outlet 52. Electronsv bombard. the resultingvapor that .fills the arc bore 48 and also enter the outlet aperture 52in the tube 51. An .arc discharge thereby set up generating ions whichare withdrawn and utilized in a manner previously described. Theintrcduction of the .entire gas charge at the anode eliminatesunsteadiness of the are at the anode region.

. Referring to Fig. there .is shown a modification O my inventionwherein the entire gas flowis directed onto the. anode. In thismodification an arc block 450 is formed of a single piece of metal, suchas copper, and is maintained at a positive potential with respect toemissive filament 46 as described heretofore. Block 45a contains twointerconnecting reservoir bores 47 and an arc chamber 48. The outputvapor from the bores 47 is directed downward and into slot 53 in baseplate 54 which is removably attached to block 45a. The charge vaporflows through slot 53 into arc chamber 48 and thereby enters arc chamber48 at the bottom and flows upwardly in arc chamber 48 toward filament46. Further, the filament 46 is sopositioned with respect to themagnetic field and the base plate 54 and slot 53 that the electronsemitted from filament 46 actually enter and impinge upon the outlet endof slot 53.

In operation of the modification of Fig. 5 an appropriate chargematerial is placed in block 45a and heated by heaters (not shown)causing vapor to be formed which travels through slot 53 cut in baseplate 54 and thence into arc chamber 48 entering at the base of arcchamber 48. Electrons emitted from filament 46 bombard the resultingvapor that fills arc chamber 48 and also enter the exit end of slot 53in base plate 54. An arc discharge directed by the magneticfield asdescribed is thereby set up generating ions which are withdrawn andutilized in a manner previously discussed. the anode eliminates theunsteadiness of the arc in the anode region.

Although I have described my invention with respect to a particularembodiment thereof, it is not limited "to this embodiment nor otherwiseexcept by the terms of the following claims.

What is claimed is:

1. In an apparatus for developing gaseous ions from a vaporizable sourcecompound, the combination of means The introduction of the entire gascharge at in the reservoir bores 47 for establishing an, ar dis hargsaid means comprising an elongated arc chamber including meansconstituting an anode for said are discharge and an electron emissivecathode spaced from said chamber at one end thereof, means forintroducing a vapor of said compound into said chamber, and bafile meansPositioned in the path of vapor flow for directing the vapors enteringsaid chamber to an end thereof opposite said cathode.

2. An apparatus for developing gaseous ions from a vaporizable sourcecompound comprising means defining an elongated region for gasionization, means forintroducing into said region a vapor of saidcompound, an anode and a cathode for establishing an arc dischargethrough said region in the direction of its elongation to provide adischarge path containing positive ions of said vapor throughout saidregion, means disposed between said anode and cathode for directing theflow of an additional supply of said vapor directly onto. the anode ofsaid discharge path.

3. A calutron comprising means forming a gas ionization chamber ofelongated form, an electron emitter disposed adjacent one, end of saidchamber, a tubular anode disposed adjacent the other end of the chamberand'havv ing an opening directed toward the electron emitter, and meansfor supplying to the tube a gas to be ionized.

4. A calutron comprising a block having open-ended parallel arc andcharge cavities, a channeled plate attached to the block and coveringone end of the cavities and communicating the charge and are cavities,and an electron emitter disposed adjacent, the other end'of the arccavity.

5. Acalutron comprising an ion source includingan elongated arc chamber,an electron emitting filamentarranged at one end of said chamber, anelectron receiving anode arranged at the other end of said chamber,means for admitting gas to be ionized to said chamber, andia baffle fordirecting part of said gas to flow across said anode.

6. In an ion source for a calutron, the combination comprising an arcblock having an elongated ionization chamber with an exit slit extendingsubstantially the length thereof, an electron emitting filament arrangedat one end of said chamber, an electron receiving anode arranged at theother end of said chamber, means for admitting a gas to be ionized tosaid chambenand means disposed between said anode and filament fordirecting a portion of said gas directly onto said anode.

References Cited in the file of this patent UNITED STATES PATENTS2,374,205 Hoskins Apr.'24, 1945 OTHER REFERENC S 'Tuve et al.: PhysicalReview, Aug. 1, 1935, vol. 48, pp. 241-243.

Timoshenko: Review of Scientific 'Instrument tn 1938,vol. 9,pP. 187 and188.

